Gear disengaging devices for worm gears



May 29, 1956 M. SANDERS GEAR DISENGAGING DEVICES FOR WORM GEARS Filed June 4, 1954 INVENTOR Maze/5 Sfl/VOEES United States Patent M GEAR DISENGAGING DEVICES FOR WORM GEARS Morris Sanders, Rochelle Park, N. J.

Application June 4, 1954, Serial No. 434,447

2 Claims. (Cl. 74405) The present invention relates to improvements in worm gears and, more specifically, to new and improved means for temporarily disengaging a worm gear wheel from a worm. For instance, if a micrometric control means is provided in a drafting machine whereby one member in said machine can be moved slowly and under firm control through either large or small angles with respect to another member in said machine, it is highly desirable to provide also a means for readily engaging or disengaging the micrometric control means so that the member or protractor arm in said machine can be rotated under micrometric control or freely rotated as may be desired.

Therefore, one object of the present invention is the provision of a device of the character described which allows the engaging and disengaging or a worm and a worm gear wheel to be carried out easily and quickly, and whichwhen the Worm engages the worm gear wheelholds the same firmly and securely in the engaged position by applying a variable leverage against the worm gear.

Another object of the present invention is the provision of a device of the character described which is constructed in such a manner that it requires only a very small space, so that it is well adapted for being installed in the head of a drafting machine or the like, although my construction is not limited to drafting machines and can be used for other purposes also.

A further object of the present invention is the provision of a device of the character described which is simple in construction, consisting of only a few inexpensive parts which can be assembled easily and quickly, and which is also handy, simple and reliable in operation as well as sturdy, durable and well adapted for the purpose for which it is intended.

With the foregoing and other objects in view which will appear as the description proceeds, the invention consists of certain novel details of construction and combinations of parts hereinafter more fully described and pointed out in the claims, it being understood that changes may be made in the construction and arrangements of parts without departing from the spirit of the invention as claimed.

In the accompanying drawing a preferred form of the invention has been shown.

In said drawing:

Figure 1 is a reduced plan view of a drafting machine of the pulley and band type having a drafting head provided with a preferred embodiment of the present invention;

Fig. 2 is a top plan view of a preferred embodiment of my invention;

Fig. 3 is a side view of the embodiment of Fig. 2;

Fig. 4 is a bottom plan view of the embodiment of Fig. 2; and

Fig. 5 is a fractional enlarged sectional view on the line 55 of Fig. 1.

Similar reference characters refer to similar parts throughout the several views.

In the drawing the numeral 1 denotes an upper elbow 2,747,423 Patented May 29, 1956 bracket, and the numeral 2 denotes a lower elbow bracket. The upper elbow bracket 1 is connected to a clamp bracket 3 by means of a longitudinal member 4, and the lower elbow bracket 2 is connected to a head bracket 5 by means of a longitudinal member 6. The clamp bracket 3 is adapted to be fastened to a drawing board (not shown), and to the head bracket 5 there are mounted rulers 7 and 8 in any suitable well-known manner. The brackets'l and 2 are connected to the brackets 3 and 5 by means of endless bands 10 and 11 respectively.

My new and improved disengageable worm gear has a base plate 12 to the center of which is securely mounted a shaft 14, that is provided with a reduced threaded end portion 15 extending through the plate 12 and secured thereto by means of a nut 17 or by any other suitable means.

A worm gear wheel 20 is rotatably mounted on the shaft 14 and is constructed and arranged for engaging with its circumferential teeth the threads of a worm 21, which is secured to, or formed as a unit with, a rod 22. A sub plate 23 is pivoted at 24 to one side of the plate 12, and a pair of lugs 25 extend from the sub plate 23. The worm 21 and the rod 22 are rotatably mounted on the lugs 25, and a knurled knob 27 is secured to the outer extremity of the rod 22.

The plate 12 is provided with a longitudinal opening or slot 30, through which extend a shoulder bolt 31 that is secured to that end of the sub plate 23 which is opposite the pivot 24.

To the other side of the plate 12 there is pivoted at 32 a lever 33 intermediate its ends. The bolt 31 extends through one end of the lever 33, while any suitable resilient means are interposed between the other end of the lever 33 and the plate 12. Said resilient means in the present instance are a U-shaped resilient member 34, one extremity of which is pivoted to the lever 33 at 35, while its other extremity is pivoted to the plate 12 at 37. This construction and arrangement of the U-shaped resilient member 34 and the lever 33 as shown will hold the parts 21, 22, 23, 25 and 27, safely in the gear engaging position, which is shown in full lines, and it also will maintain the same in the disengaging position indicated in dashand-dotted lines in Figs. 2 and 4. The pressure of the worm 21 exerted upon the worm gear wheel 20 when in engaging position depends upon the location of the pivot points 31 and 32 and their distance from each other, so that this pressure can be altered by changing the locations of said pivot points.

If my new and improved device is to be used for a drafting machine, as in the instance shown, the plate 12 is provided with threaded holes 40 for receiving screws 41 (Fig. 5) by means of which an operating knob 42 of a drafting machine can be secured thereto; moreover, a cylindrical member 43, through which extends the shaft 14, is extended from one side of the worm gear wheel 20 and is provided with an increased portion 44 that is secured to the head of the drafting machine by means of screws, which extend through holes 47 in the portion 44; finally a disk 50 is firmly secured to the outer extremity of the shaft 14, which extends through the entire head of the drafting machine, and holes 51 are provided in the disk 50 for extending therethrough rivets by means of which a support member 53 for rulers is secured to the disk 50.

Since certain changes may be made in the above article and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope ofthe invention which as a matter of language might be said to fall therebetween.

Having thus fully described my said invention, what I claimas new and desire'tosecure by Letters Patient is:

1. A gear disengaging device for a worm gear, which hasageartwheel'normally engaged by a worm, comprising a base member on which said gear wheel is; rotat-ably mounted and which is provided with a perforation, a bracket member on 'whichsaid worm is rotatably mounted being pivoted to one side of said base member adjacent said gear Wheel soas to allow said worm to engage said gear wheel in a first pivot position of said bracket member and to disengage said worm from said gear wheel in a second pivotposition ofsaid bracket member, a lever pivoted; intermediate its ends to the other side of said base member; a-connectingmember extending through the perforation in said base member and connecting said bracket member to one end'of said lever in such a mannet as to cause a swinging movement of said lever when has a gear wheel normally engaged by a worm, comprising a base member on which said gear Wheel isrotatably mounted and which is provided withta' perforation, a bracket member on which said worm is rotatably mounted being pivoted to one side of said base member adjacent said gear wheel so as to allow said worm to engage said gear wheel in a first pivot position of said bracket member and to disengage said worm from said gear wheel in a second pivot position of said bracket member, a; lever pivoted intermediate its ends to the other side of said base member, a connecting member extending through the perforation in said base member and connecting said bracket member to one end of said lever in-such. a manner as to cause a swinging movement of said lever when said bracket member swings round its pivot, and a U-shaped resilient member having one of its extremities pivoted to the other end of said lever and its other extremity pivoted to said base member tending to maintain said bracket member in its first and second pivot positions relative tosaid base member.

References Cited in the file of this patent UNITED STATES PATENTS 2,310,623 Estey Feb. 9,. 1943, 

